The use of prosthetic devices for treatment of bone injuries/illnesses is continuously expanding with an increasingly active and aging population. Among those disorders are osteoporosis, Paget's disease of bone and joints, and arthritis. All these disorders may cause limited mobility and often, particularly in the elderly, can result in death due to resulting bone fractures. When not fatal, these disorders still often require surgical bone or joint replacement of hips, knees, elbows, and other joints.
The major problem associated with the bone replacement, especially for the defects of both the bone and the adjacent cartilage, is the lack of a suitable material which would have the same or similar properties as bone but that would also be compatible with the human body. The properties which the bone or joint replacement material need to possess include biocompatibility, porosity, strength, durability, elasticity and, in order to prevent wear in joint areas and to prevent or allow tissue attachment in other areas, as need be, a possibility to be surface finished. Therefore, such material must have approximately the same porosity, weight and structure and must not be more fragile or more brittle than the normal bone.
Current research is focused around the use of porous degradable synthetic polymer materials as osteochondral plug scaffolds to allow regeneration of both the subchondral bone and hylan cartilage surface. Some have even added in small amounts of calcium phosphate or calcium sulfate directly blended into the polymer scaffold to facilitate bone formation. Animal studies show that the underlying subchondral bone results in either large unresorbed areas of polymer or void spaces filled with fluid or fibrous tissue. This void space in the subchondral bone can often result in a collapse of the upper cartilage surface and suboptimal repair of the hylan cartilage layer with the host hylan cartilage. Thus, the “one size fits all” approach hinders implant incorporation into the host bone and cartilage and eventual replacement by natural host tissue.
Accordingly, there is a need for improved osteochondral implantable devices suitable for repair of bone/cartilage defects.